JPH0752133B2 - Device for measuring web tension - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring web tension, and more particularly to a device for measuring web tension for a paper web of a rotary web printing press.

[0002]

PRIOR ART German Federal Patent No. 1187096
The document discloses a device for measuring and adjusting the pulling force of a paper web moving via rollers, said device being arranged at right angles to the direction of movement of the web and comprising a plurality of devices. It has a tubular part with nozzles or holes, which is connected to the pressurized air container via a throttle valve. The magnitude of the pressure in the tubular section is then a measure for the respective web tension, i.e. in this case the section with the nozzles or holes is designed as a rotary cylinder, which has a web speed. It has a plurality of holes which are uniformly distributed on the peripheral wall, and of which only the holes located in the contact area with the web are active. The disadvantages of this device are as follows. The known device thus reduces the blurring between the individual printing units by changing the orientation of the paper web to be measured, based on being completely or at least partly wrapped around a rotating measuring cylinder. Will occur.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a device for measuring the web tension in a contactless manner, in which the deviation of the paper web from the web conveying direction is small and a high measurement accuracy can be obtained. It is to be.

[0004]

In order to solve this problem, in the structure of the present invention, two tubes are provided which are spaced apart from each other and extend at right angles to the paper movement direction and which are provided with a plurality of blow air nozzles. Are arranged at the free ends of the two holding arms which are centrally mounted on the frame fixing and measure the bending between the free ends of the holding arms of the pipe and the central bearing of the holding arms respectively. And a paper web is wound around the two tubes alternately in the web movement direction at a winding angle up and down, and the value of the bending of the free end of the holding arm can be evaluated. , And a value that is directly proportional to the paper web tension.

[0005]

The device constructed according to the present invention has the following advantages. That is, the device according to the invention provides a high registration accuracy when measuring the web tension, due to the minimal deviation of the paper web. Further, since the measurement is performed in a contactless manner, the paper web immediately after printing can be prevented from being rubbed and stained. Furthermore,
Due to the arrangement of the two weighing cells, a high measuring accuracy is obtained. By using the device according to the invention, the movement of the paper web is calmed down, which helps to avoid the blurring phenomenon. Furthermore, the device according to the invention can advantageously be used for automatically performing the adjusting or safety function by comparing the setpoint value and the actual value via a computer. The safety function is, for example,
It can be carried out on the paper winder or when the paper web breaks. The device according to the invention can also be used in scrap printing presses, newspaper printing presses, telephone directory printing presses or flexographic printing presses.

[0006]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a side view schematically showing a web-fed rotary printing press for printing of scraps. The paper web 1 coming from the paper web changer 2 passes through the drawing device 3, the printing units 5; 6; 7; 8 and the drying oven 9, and reaches the folding device 12 via the cooling zone 11, which folding device 12 It is transported further from 12 in a known manner. Measuring devices 13; 14 according to the invention are arranged between the printing units 6, 7 and in front of the drying oven 9, respectively, which measuring devices 13; 14 are shown in FIGS. 2 and 3. A detailed description will be given later with reference to a sectional view or a plan view. In that case, only the measuring device 13 will be described as a representative for all equally configured measuring devices.

Holding arms 18 and 19 extending parallel to each other are fixed to the frame-fixed supports 16 and 17 by means of screws 21 at their centers. The free ends 22; 23; 24; 25 of the holding arms 18; 19 extend axially parallel to the cylinder of the printing units 5-8 via the clamp holders 27; 28; 29; It receives tubes 33; 34 with openings or holes 32. These holes 32 extend in two rows in the axial direction of the tubes 33; 34 and are arranged only on the contact surface between the paper web 1 and the tubes 33; 34. Tube 33; 3
The contact surface at the outer periphery of 4 corresponds to an angle β of about 25 °. The tubes 33; 34 are clamped with screws 20 in the clamp holders 27-30. Tube 33; 34
Each of them is tightly closed at one end and is connected at the other end to a T-shaped air supply 38 via hoses 36 and 37. The air supply passage 38 is connected to a blow air device in the printing machine via a valve (not shown). Hoses 36; 37
Are fixed using hose bands 39 at their connection points. The air supply passage 38 is connected to the support 16 via a holder 41. It is also possible to supply air to the pipes 33; 34 from both ends, that is to say in this case it is necessary to arrange the hoses 36; 37 and the T-shaped air supply passage 38 in double.

The holding arms 18 and 19 each have extension measuring strips 42 to 45 between a central fixed part 21 and clamp holders 27 to 30 arranged at the free ends 22 to 25. The tension of the paper web 1 causes the holding arms 18; 19 to bend somewhat in the direction of arrow C or D, to which the stretch-measuring strips 42-45 react.

The evaluation circuit assigned to the stretch measuring strips 42 to 45 is shown in FIG. This evaluation circuit is a known double bridge circuit 47.
The resistance of 7 corresponds to the stretch measuring strips 42-45. The output part of the double bridge circuit 47 is connected via an RC balance circuit 48, an amplifier 49 and a bandpass filter 51, or a frequency generator 52, a 90 ° phase shifter 53 and a sine quadrature converter 54.
It is connected to the demodulator 56 having a proper phase via the and, and is further connected to the display device 58 via the low-pass filter 57. The components 48 to 57 are arranged outside the measuring device 13, i.e. in a casing (not shown). The display device 58 is arranged, for example, in a printing press guide stand or in another central location.

In FIG. 2, a dashed line shows a variant embodiment relating to the arrangement of the metering cells. In this embodiment, the inductive type distance pickups 61 to 64 have a holding arm 18;
The holders 65 and 66 are arranged at a prescribed distance from the ends 22 to 25 of the holder 19.
5; 66 itself is connected to the frame-fixed supports 16; 17 by force connection. Distance pickup 61-64
Is connected to a known beam frequency and measurement amplifier, not shown, where it is supplemented by a precision resistor leading to a Wheatstone bridge. The shift of the plunger mover detunes the pre-balanced bridge. The measurement signal produced by the distance pick-ups 61-64 is directly proportional to the shift of the armature and is therefore a measure for the distance of the holding arms 18 and 19 which coincide with the plunger armature. Then, after amplification, a readable indication of the aura and amplitude, as indicated on the display 58 as shown schematically, is obtained, that is to say the deviation to be measured based on the web tension. In this case, the average value is formed as the total number. This allows the operator to introduce appropriate measures such as, for example, correction of web tension using a pull cylinder.
This is also due to the adjustment control carried out via a calculator (not shown) in the press guide stand,
It can also be done automatically.

5 and 6, respectively, a roll offset printing machine for a newspaper printing machine or a flexographic printing machine is schematically shown in side view as an example of use for arranging the measuring device 69; 70 according to the invention. It is shown. In this case, as shown in FIG. 7, the paper web 1 is deflected at an angle α with respect to the vertical as it circulates through the measuring device 67. This angle α is about 6 °. This is
The same applies to the deviation of the paper web in the other measuring devices 13; 14; 70 mentioned above.

The spacing b between both tubes 33; 34 is as follows: that this spacing b is below the natural frequency of the paper web 1 and the natural frequency of the measuring devices 13; 14; 69; It is dimensioned.

[Brief description of drawings]

1 is a side view schematically showing a web-fed rotary printing press equipped with a device according to the invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a plan view from above of the device according to the invention.

FIG. 4 is a schematic diagram showing an electrical evaluation circuit for stretching measurement in a holder.

FIG. 5 is a side view schematically showing a roll offset printing press equipped with the device according to the present invention.

FIG. 6 is a side view schematically showing a flexographic printing machine equipped with a device according to the invention.

FIG. 7 is a schematic view showing a state of deviation of the paper web.

[Explanation of symbols]

1 paper web, 2 paper roll changer, 3 retractor, 5, 6, 7, 8 printing unit, 9 drying oven,
11 cooling section, 12 folding device, 13,14 measuring device, 16,17 support, 18,19 holding arm, 20,21 screw, 22,23,24,25
Free end, 27, 28, 29, 30 Clamp holder,
32 nozzles or holes, 33, 34 tubes, 3
6,37 Hose, 38 Air supply path, 39 Hose band, 41 Holder, 42, 43, 44, 45
Stretch measurement strip, 47 double bridge circuit, 48R
C balanced circuit, 49 amplifier, 51 bandpass filter,
52 frequency generator, 53 phase advancer, 54 sinusoidal quadrature converter, 56 demodulator 56, 57 low-pass filter, 58 display device, 61, 62, 63, 64 distance pickup, 65, 66 holder, 67 web rotary printing press , 68 flexographic printing machine, 69, 70
Measuring device, A conveyance direction, C, D bending direction, b
Interval, α, β angle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Erhard Herbert Geckner, Federal Republic of Germany Iberstadt Wilhelm-Dorres-Strasse 18 (56) Reference JP-A-2-114141 (JP, A) JP-A-3-246433 (JP) , A) Actually open 63-48132 (JP, U) Actually open 1-95643 (JP, U) Japanese Patent Sho 53-41546 (JP, B2)

Claims (6)

[Claims] 1. A device for measuring web tension for a paper web, comprising two spaced air gaps and extending at right angles to the direction of paper movement and comprising a plurality of blow air nozzles (32). The free ends (22; 23; 24; 2) of the two holding arms (18; 19) in which the tubes (33; 34) are supported centrally in a frame fixed manner.
5), the free ends (22; 23; 24; 25) of the retaining arms (18; 19) of the tubes (33; 34)
And the central bearing (21; 1) of the holding arm (18; 19)
6; 17) and the elements (42; 43; 44; 45; 61; 62; 63; 6 for measuring bending, respectively).
4) is provided, and the paper web (1) is wound around the two tubes (33; 34) alternately in the web movement direction (A) at an upper and lower winding angle (β), and a holding arm. Free end (22; 2) of (18; 19)
Device for measuring web tension, characterized in that the value of bending (C, D) of 3; 24; 25) can be evaluated and can be evaluated as a value directly proportional to the paper web tension. 2. Device according to claim 1, characterized in that an air cushion is arranged between the nozzles (32) of the tubes (33; 34). 3. The pipe (33; 34) is a conduit (36; 3).
Device according to claim 1 or 2, which is connected to the blow air device via 7) and a valve. 4. Element for measuring bending (42; 4)
3; 44; 45) consisting of a stretch measuring strip which comprises a free end (22; 23; 24; 25) of the holding arm (18; 19) and a central fixed part ( 21; 1
6. The device according to any one of claims 1 to 3, which is arranged between 6) and 17). 5. Element for measuring bending (61; 6)
2; 63; 64) consisting of an inductive distance pickup, said distance pickup comprising a holding arm (18;
Device according to any one of claims 1 to 3, which is arranged in a fixed frame at a defined distance to 19). 6. Paper web for tubes (33; 34)
The device according to any one of claims 1 to 5, wherein the winding angle (β) of (1) is 20 to 30 °.